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Narasaraju T, Ravi Y, Jonsson CB, Chow VTK. High-dose corticosteroid therapy in COVID-19: the RECOVERY trial. Lancet 2024; 403:1338-1339. [PMID: 38582562 DOI: 10.1016/s0140-6736(23)02884-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 12/21/2023] [Indexed: 04/08/2024]
Affiliation(s)
- Teluguakula Narasaraju
- Regional Biocontainment Laboratory, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
| | - Yazhini Ravi
- Department of Surgery, University of Connecticut Health, Farmington, CT, USA
| | - Colleen B Jonsson
- Regional Biocontainment Laboratory, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Vincent T K Chow
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore
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2
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Narasaraju T, Neeli I, Criswell SL, Krishnappa A, Meng W, Silva V, Bila G, Vovk V, Serhiy Z, Bowlin GL, Meyer N, Luning Prak ET, Radic M, Bilyy R. Neutrophil Activity and Extracellular Matrix Degradation: Drivers of Lung Tissue Destruction in Fatal COVID-19 Cases and Implications for Long COVID. Biomolecules 2024; 14:236. [PMID: 38397474 PMCID: PMC10886497 DOI: 10.3390/biom14020236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/04/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Pulmonary fibrosis, severe alveolitis, and the inability to restore alveolar epithelial architecture are primary causes of respiratory failure in fatal COVID-19 cases. However, the factors contributing to abnormal fibrosis in critically ill COVID-19 patients remain unclear. This study analyzed the histopathology of lung specimens from eight COVID-19 and six non-COVID-19 postmortems. We assessed the distribution and changes in extracellular matrix (ECM) proteins, including elastin and collagen, in lung alveoli through morphometric analyses. Our findings reveal the significant degradation of elastin fibers along the thin alveolar walls of the lung parenchyma, a process that precedes the onset of interstitial collagen deposition and widespread intra-alveolar fibrosis. Lungs with collapsed alveoli and organized fibrotic regions showed extensive fragmentation of elastin fibers, accompanied by alveolar epithelial cell death. Immunoblotting of lung autopsy tissue extracts confirmed elastin degradation. Importantly, we found that the loss of elastin was strongly correlated with the induction of neutrophil elastase (NE), a potent protease that degrades ECM. This study affirms the critical role of neutrophils and neutrophil enzymes in the pathogenesis of COVID-19. Consistently, we observed increased staining for peptidyl arginine deiminase, a marker for neutrophil extracellular trap release, and myeloperoxidase, an enzyme-generating reactive oxygen radical, indicating active neutrophil involvement in lung pathology. These findings place neutrophils and elastin degradation at the center of impaired alveolar function and argue that elastolysis and alveolitis trigger abnormal ECM repair and fibrosis in fatal COVID-19 cases. Importantly, this study has implications for severe COVID-19 complications, including long COVID and other chronic inflammatory and fibrotic disorders.
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Affiliation(s)
- Teluguakula Narasaraju
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA; or (T.N.); (I.N.); (V.S.)
- Department of Microbiology, Adichunchanagiri Institute of Medical Sciences, Center for Research and Innovation, Adichunchanagiri University, Mandya 571448, India
| | - Indira Neeli
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA; or (T.N.); (I.N.); (V.S.)
| | - Sheila L. Criswell
- Department of Diagnostic and Health Sciences, University of Tennessee Health Science Center, Memphis, TN 38163, USA;
| | - Amita Krishnappa
- Department of Pathology, Adichunchanagiri Institute of Medical Sciences, Adichunchanagiri University, Mandya 571448, India;
| | - Wenzhao Meng
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (W.M.); (E.T.L.P.)
| | - Vasuki Silva
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA; or (T.N.); (I.N.); (V.S.)
| | - Galyna Bila
- Department of Histology, Cytology, Histology & Embryology, Danylo Halytsky Lviv National Medical University, 79010 Lviv, Ukraine; (G.B.); (R.B.)
| | - Volodymyr Vovk
- Department of Pathological Anatomy and Forensic Medicine, Danylo Halytsky Lviv National Medical University, 79010 Lviv, Ukraine;
- Lviv Regional Pathological Anatomy Office, CU ENT (Pulmonology Lviv Regional Diagnostic Center), 79000 Lviv, Ukraine;
| | - Zolotukhin Serhiy
- Lviv Regional Pathological Anatomy Office, CU ENT (Pulmonology Lviv Regional Diagnostic Center), 79000 Lviv, Ukraine;
| | - Gary L. Bowlin
- Department of Biomedical Engineering, University of Memphis, Memphis, TN 38152, USA;
| | - Nuala Meyer
- Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;
- Pulmonary, Allergy, and Critical Care Medicine and Center for Translational Lung Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eline T. Luning Prak
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (W.M.); (E.T.L.P.)
- Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;
| | - Marko Radic
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA; or (T.N.); (I.N.); (V.S.)
| | - Rostyslav Bilyy
- Department of Histology, Cytology, Histology & Embryology, Danylo Halytsky Lviv National Medical University, 79010 Lviv, Ukraine; (G.B.); (R.B.)
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3
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Ong JWJ, Tan KS, Lee JJX, Seet JE, Choi HW, Ler SG, Gunaratne J, Narasaraju T, Sham LT, Patzel V, Chow VT. Differential effects of microRNAs miR-21, miR-99 and miR-145 on lung regeneration and inflammation during recovery from influenza pneumonia. J Med Virol 2023; 95:e29286. [PMID: 38087452 DOI: 10.1002/jmv.29286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 10/10/2023] [Accepted: 11/18/2023] [Indexed: 12/18/2023]
Abstract
In a mouse model of influenza pneumonia, we previously documented that proliferating alveolar type II (AT2) cells are the major stem cells involved in early lung recovery. Profiling of microRNAs revealed significant dysregulation of specific ones, including miR-21 and miR-99a. Moreover, miR-145 is known to exhibit antagonism to miR-21. This follow-up study investigated the roles of microRNAs miR-21, miR-99a, and miR-145 in the murine pulmonary regenerative process and inflammation during influenza pneumonia. Inhibition of miR-21 resulted in severe morbidity, and in significantly decreased proliferating AT2 cells due to impaired transition from innate to adaptive immune responses. Knockdown of miR-99a culminated in moderate morbidity, with a significant increase in proliferating AT2 cells that may be linked to PTEN downregulation. In contrast, miR-145 antagonism did not impact morbidity nor the proliferating AT2 cell population, and was associated with downregulation of TNF-alpha, IL1-beta, YM1, and LY6G. Hence, a complex interplay exists between expression of specific miRNAs, lung regeneration, and inflammation during recovery from influenza pneumonia. Inhibition of miR-21 and miR-99a (but not miR-145) can lead to deleterious cellular and molecular effects on pulmonary repair and inflammatory processes during influenza pneumonia.
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Affiliation(s)
- Joe Wee Jian Ong
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Kai Sen Tan
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | | | - Ju Ee Seet
- Department of Pathology, National University of Singapore, Singapore
| | - Hyung Won Choi
- Department of Medicine, National University of Singapore, Singapore
| | | | | | - Teluguakula Narasaraju
- Adichunchanagiri Institute of Medical Sciences, Adichunchanagiri University, Karnataka, India
| | - Lok-To Sham
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Volker Patzel
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Vincent T Chow
- Infectious Diseases Translational Research Program, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Narasaraju T, Krishnappa A, Radic M, Chow VTK. Efficacy and Safety of Ensovibep for Adults Hospitalized With COVID-19. Ann Intern Med 2023; 176:eL220455. [PMID: 36802894 DOI: 10.7326/l22-0455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/22/2023] Open
Affiliation(s)
| | - Amita Krishnappa
- Adichunchanagiri Institute of Medical Sciences, Karnataka, India
| | - Marko Radic
- University of Tennessee Health Science Center, Memphis, Tennessee
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Narayanan S, Ritchey JC, Patil G, Narasaraju T, More S, Malayer J, Saliki J, Kaul A, Agarwal PK, Ramachandran A. SARS-CoV-2 Genomes From Oklahoma, United States. Front Genet 2021; 11:612571. [PMID: 33613621 PMCID: PMC7886813 DOI: 10.3389/fgene.2020.612571] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/31/2020] [Indexed: 11/13/2022] Open
Abstract
Genomic sequencing has played a major role in understanding the pathogenicity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the current pandemic, it is essential that SARS-CoV-2 viruses are sequenced regularly to determine mutations and genomic modifications in different geographical locations. In this study, we sequenced SARS-CoV-2 from five clinical samples obtained in Oklahoma, United States during different time points of pandemic presence in the state. One sample from the initial days of the pandemic in the state and four during the peak in Oklahoma were sequenced. Previously reported mutations including D614G in S gene, P4715L in ORF1ab, S194L, R203K, and G204R in N gene were identified in the genomes sequenced in this study. Possible novel mutations were also detected in the S gene (G1167V), ORF1ab (A6269S and P3371S), ORF7b (T28I), and ORF8 (G96R). Phylogenetic analysis of the genomes showed similarity to other SARS-CoV-2 viruses reported from across the globe. Structural characterization indicates that the mutations in S gene possibly influences conformational flexibility and motion of the spike protein, and the mutations in N gene are associated with disordered linker region within the nucleocapsid protein.
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Affiliation(s)
- Sai Narayanan
- Oklahoma Animal Disease Diagnostic Laboratory, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - John C. Ritchey
- Oklahoma Animal Disease Diagnostic Laboratory, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Girish Patil
- Oklahoma Animal Disease Diagnostic Laboratory, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Teluguakula Narasaraju
- Oklahoma Animal Disease Diagnostic Laboratory, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Sunil More
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Jerry Malayer
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Jeremiah Saliki
- Oklahoma Animal Disease Diagnostic Laboratory, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Anil Kaul
- Center for Health Sciences, Oklahoma State University, Tulsa, OK, United States
| | - Pratul K. Agarwal
- Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
- High-Performance Computing Center, Oklahoma State University, Stillwater, OK, United States
| | - Akhilesh Ramachandran
- Oklahoma Animal Disease Diagnostic Laboratory, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
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6
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Affiliation(s)
- Teluguakula Narasaraju
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma (T.N.)
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7
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Narasaraju T, Tang BM, Herrmann M, Muller S, Chow VTK, Radic M. Neutrophilia and NETopathy as Key Pathologic Drivers of Progressive Lung Impairment in Patients With COVID-19. Front Pharmacol 2020; 11:870. [PMID: 32581816 PMCID: PMC7291833 DOI: 10.3389/fphar.2020.00870] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 05/27/2020] [Indexed: 12/21/2022] Open
Abstract
There is an urgent need for new therapeutic strategies to contain the spread of the novel coronavirus disease 2019 (COVID-19) and to curtail its most severe complications. Severely ill patients experience pathologic manifestations of acute respiratory distress syndrome (ARDS), and clinical reports demonstrate striking neutrophilia, elevated levels of multiple cytokines, and an exaggerated inflammatory response in fatal COVID-19. Mechanical respirator devices are the most widely applied therapy for ARDS in COVID-19, yet mechanical ventilation achieves strikingly poor survival. Many patients, who recover, experience impaired cognition or physical disability. In this review, we argue the need to develop therapies aimed at inhibiting neutrophil recruitment, activation, degranulation, and neutrophil extracellular trap (NET) release. Moreover, we suggest that currently available pharmacologic approaches should be tested as treatments for ARDS in COVID-19. In our view, targeting host-mediated immunopathology holds promise to alleviate progressive pathologic complications of ARDS and reduce morbidities and mortalities in severely ill patients with COVID-19.
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Affiliation(s)
- Teluguakula Narasaraju
- College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Benjamin M. Tang
- Department of Intensive Care Medicine, Nepean Hospital, Sydney, NSW, Australia
| | - Martin Herrmann
- Department of Internal Medicine 3, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sylviane Muller
- CNRS-University of Strasbourg, Biotechnology and Cell Signaling, Illkirch, France
- Laboratory of Excellence Medalis, Institut de science et d'ingénierie supramoléculaire, and University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, France
| | - Vincent T. K. Chow
- Department of Microbiology and Immunology, Infectious Diseases Program, School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore
| | - Marko Radic
- Department of Microbiology, Immunology and Biochemistry, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
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Rudd JM, Pulavendran S, Ashar HK, Ritchey JW, Snider TA, Malayer JR, Marie M, Chow VTK, Narasaraju T. Neutrophils Induce a Novel Chemokine Receptors Repertoire During Influenza Pneumonia. Front Cell Infect Microbiol 2019; 9:108. [PMID: 31041196 PMCID: PMC6476945 DOI: 10.3389/fcimb.2019.00108] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 03/28/2019] [Indexed: 12/21/2022] Open
Abstract
Exaggerated host innate immune responses have been implicated in severe influenza pneumonia. We have previously demonstrated that excessive neutrophils recruited during influenza infection drive pulmonary pathology through induction of neutrophil extracellular traps (NETs) and release of extracellular histones. Chemokine receptors (CRs) are essential in the recruitment and activation of leukocytes. Although neutrophils have been implicated in influenza pathogenesis, little is known about their phenotypic changes, including expression of CRs occurring in the infected -lung microenvironment. Here, we examined CC and CXC CRs detection in circulating as well as lung-recruited neutrophils during influenza infection in mice using flow cytometry analyses. Our studies revealed that lung-recruited neutrophils displayed induction of CRs, including CCR1, CCR2, CCR3, CCR5, CXCR1, CXCR3, and CXCR4, all of which were marginally induced in circulating neutrophils. CXCR2 was the most predominant CR observed in both circulating and lung-infiltrated neutrophils after infection. The stimulation of these induced CRs modulated neutrophil phagocytic activity, ligand-specific neutrophil migration, bacterial killing, and NETs induction ex vivo. These findings indicate that neutrophils induce a novel CR repertoire in the infectious lung microenvironment, which alters their functionality during influenza pneumonia.
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Affiliation(s)
- Jennifer M Rudd
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Sivasami Pulavendran
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Harshini K Ashar
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Jerry W Ritchey
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Timothy A Snider
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Jerry R Malayer
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Montelongo Marie
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
| | - Vincent T K Chow
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore
| | - Teluguakula Narasaraju
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States
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Moorthy AN, Tan KB, Wang S, Narasaraju T, Chow VT. Effect of High-Fat Diet on the Formation of Pulmonary Neutrophil Extracellular Traps during Influenza Pneumonia in BALB/c Mice. Front Immunol 2016; 7:289. [PMID: 27531997 PMCID: PMC4969943 DOI: 10.3389/fimmu.2016.00289] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 07/19/2016] [Indexed: 11/13/2022] Open
Abstract
Obesity is an independent risk factor for severe outcome of influenza infection. Higher dietary fat consumption has been linked to greater morbidity and severe influenza in mouse models. However, the extent of generation of neutrophil extracellular traps (NETs or NETosis) in obese individuals during influenza pneumonia is hitherto unknown. This study investigated pulmonary NETs generation in BALB/c mice fed with high-fat diet (HFD) and low-fat diet (LFD), during the course of influenza pneumonia. Clinical disease progression, histopathology, lung reactive oxygen species, and myeloperoxidase activity were also compared. Consumption of HFD over 18 weeks led to significantly higher body weight, body mass index, and adiposity in BALB/c mice compared with LFD. Lethal challenge of mice (on HFD and LFD) with influenza A/PR/8/34 (H1N1) virus led to similar body weight loss and histopathologic severity. However, NETs were formed at relatively higher levels in mice fed with HFD, despite the absence of significant difference in disease progression between HFD- and LFD-fed mice.
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Affiliation(s)
- Anandi Narayana Moorthy
- Department of Microbiology and Immunology, School of Medicine, National University of Singapore, National University Health System , Singapore
| | - Kong Bing Tan
- Department of Pathology, National University Hospital, National University of Singapore, National University Health System , Singapore
| | - Shi Wang
- Department of Pathology, National University Hospital, National University of Singapore, National University Health System , Singapore
| | | | - Vincent T Chow
- Department of Microbiology and Immunology, School of Medicine, National University of Singapore, National University Health System , Singapore
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Affiliation(s)
| | - Ashar Harshini
- Center for Veterinary Health Sciences, Oklahoma State University, Oklahoma, USA
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Narasaraju T, Yang E, Samy R, Tan K, Moorthy A, Phoon M, Rooijen N, Choi H, Chow V. Combination Therapy with Hepatocyte Growth Factor and Oseltamivir Confers Enhanced Protection Against Influenza Viral Pneumonia. Curr Mol Med 2014; 14:690-702. [DOI: 10.2174/1566524014666140603103138] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 11/24/2013] [Accepted: 01/31/2014] [Indexed: 11/22/2022]
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Liew A, Narasaraju T, Phoon M, Wang S, Tan K, Chow V. Caspase-1-Deficient Mice are More Susceptible Than Wild-Type Mice to Pneumonia Induced by Influenza A (H1N1). EUR J INFLAMM 2014. [DOI: 10.1177/1721727x1401200112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Although inflammasome-mediated caspase-1 activity and subsequent maturation of IL-1β are critical in host immune response against influenza, their roles in lung pathogenesis are not completely understood. Enhanced susceptibility of caspase-1-deficient mice to influenza has been attributed to decreased inflammation and augmented epithelial damage, while increased IL-1β release has been shown to exacerbate lung pathology. We challenged caspase-1-knockout and wild-type mice with high doses of influenza A (H1N1) virus (500 pfu). Only 10% mortality occurred in wild-type mice, in contrast to 40% mortality in caspase-1-knockout mice which exhibited severe pathologic manifestations as a result of overwhelming inflammatory and cytokine/chemokine responses. Infected caspase-1 knockout mice revealed neutrophil-dominant recruitment and elevated apoptotic inflammatory cells in the lungs, while 20% of these animals displayed focal lymphocytic infiltrates in the brains suggestive of mild focal encephalitis. In infected caspase-1 knockout mice, cytokine/chemokine levels were reduced at 3 days post-infection, but robust increase in the levels of TNF-α, IL-6, MIP-1α, MCP-1, MIP-1β and RANTES were observed at 6 days post-infection, coinciding with exaggerated neutrophil influx. These results support our previous findings implicating excessive neutrophil infiltration in pathologic complications during influenza pneumonia. In addition, we observed an induction of IL-1β release in caspase-1 knock-out mice at 6 days post-infection, indicating the involvement of caspase-1-independent activation of IL-1β. Microarray analyses of the lungs of infected caspase-1 knockout mice revealed upregulation of immune and inflammatory genes including CCL8, CCL4, IFN-γ, ICOS, PRF-1, KLRA4, KLRA7, KLRA18, NKG7, LTB4R and PTX3. Collectively, our data suggest that caspase-1-mediated effects are critical against severe influenza infection which can also trigger robust caspase-1-independent inflammatory responses, thus alluding to the complexity of innate immune regulation.
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Affiliation(s)
- A.A. Liew
- Host and Pathogen Interactivity Laboratory, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Singapore
| | - T. Narasaraju
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma, USA
| | - M.C. Phoon
- Host and Pathogen Interactivity Laboratory, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Singapore
| | - S. Wang
- Department of Pathology, National University Health System, Singapore
| | - K.B. Tan
- Department of Pathology, National University Health System, Singapore
| | - V.T. Chow
- Host and Pathogen Interactivity Laboratory, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Singapore
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Narayana Moorthy A, Narasaraju T, Rai P, Perumalsamy R, Tan KB, Wang S, Engelward B, Chow VTK. In vivo and in vitro studies on the roles of neutrophil extracellular traps during secondary pneumococcal pneumonia after primary pulmonary influenza infection. Front Immunol 2013; 4:56. [PMID: 23467809 PMCID: PMC3587798 DOI: 10.3389/fimmu.2013.00056] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/12/2013] [Indexed: 12/31/2022] Open
Abstract
Seasonal influenza virus infections may lead to debilitating disease, and account for significant fatalities annually worldwide. Most of these deaths are attributed to the complications of secondary bacterial pneumonia. Evidence is accumulating to support the notion that neutrophil extracellular traps (NETs) harbor several antibacterial proteins, and trap and kill bacteria. We have previously demonstrated the induction of NETs that contribute to lung tissue injury in severe influenza pneumonia. However, the role of these NETs in secondary bacterial pneumonia is unclear. In this study, we explored whether NETs induced during pulmonary influenza infection have functional significance against infections with Streptococcus pneumoniae and other bacterial and fungal species. Our findings revealed that NETs do not participate in killing of Streptococcus pneumoniae in vivo and in vitro. Dual viral and bacterial infection elevated the bacterial load compared to animals infected with bacteria alone. Concurrently, enhanced lung pathogenesis was observed in dual-infected mice compared to those challenged with influenza virus or bacteria alone. The intensified NETs in dual-infected mice often appeared as clusters that were frequently filled with partially degraded DNA, as evidenced by punctate histone protein staining. The severe pulmonary pathology and excessive NETs generation in dual infection correlated with exaggerated inflammation and damage to the alveolar-capillary barrier. NETs stimulation in vitro did not significantly alter the gene expression of several antimicrobial proteins, and these NETs did not exhibit any bactericidal activity. Fungicidal activity against Candida albicans was observed at similar levels both in presence or absence of NETs. These results substantiate that the NETs released by primary influenza infection do not protect against secondary bacterial infection, but may compromise lung function.
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Affiliation(s)
- Anandi Narayana Moorthy
- Department of Microbiology, Infectious Diseases Program, National University of Singapore Kent Ridge, Singapore
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Ng HH, Narasaraju T, Phoon MC, Sim MK, Seet JE, Chow VT. Doxycycline treatment attenuates acute lung injury in mice infected with virulent influenza H3N2 virus: involvement of matrix metalloproteinases. Exp Mol Pathol 2012; 92:287-95. [PMID: 22421441 DOI: 10.1016/j.yexmp.2012.03.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 02/20/2012] [Accepted: 03/01/2012] [Indexed: 12/15/2022]
Abstract
Acute respiratory distress syndrome, a severe form of acute lung injury (ALI), is a major cause of death during influenza pneumonia. We have provided evidence for the involvement of recruited neutrophils, their toxic enzymes such as myeloperoxidase and matrix metalloproteinases (MMPs), and neutrophil extracellular traps in aggravating alveolar-capillary damage. In this study, we investigated the effects of doxycycline (DOX), an inhibitor of MMPs, on influenza-induced ALI. BALB/c mice were infected with a sublethal dose of mouse-adapted virulent influenza A/Aichi/2/68 (H3N2) virus, and administered daily with 20mg/kg or 60 mg/kg DOX orally. The effects of DOX on ALI were determined by measuring inflammation, capillary leakage, and MMP activities. Furthermore, levels of T1-α (a membrane protein of alveolar type I epithelium) and thrombomodulin (an endothelial protein) in the bronchoalveolar lavage fluid were evaluated by Western blot analysis. Our results demonstrate significantly decreased inflammation and protein leakage in the lungs after DOX treatment. Levels of MMP-2 and MMP-9 activity, T1-α and thrombomodulin were also diminished in the DOX-treated group. These findings were corroborated by histopathologic analyses, which demonstrated significant reduction in lung damage. Although DOX treatment reduced ALI, there were no effects on virus titers and body weights. Taken together, these results demonstrate that DOX may be useful in ameliorating ALI during influenza pneumonia. Further studies are warranted to determine whether DOX can be used in combination with anti-viral agents to alleviate severe influenza pneumonia.
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Affiliation(s)
- H H Ng
- Infectious Diseases Program, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Singapore
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15
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Ivan FX, Rajapakse JC, Welsch RE, Rozen SG, Narasaraju T, Xiong GM, Engelward BP, Chow VT. Differential pulmonary transcriptomic profiles in murine lungs infected with low and highly virulent influenza H3N2 viruses reveal dysregulation of TREM1 signaling, cytokines, and chemokines. Funct Integr Genomics 2011; 12:105-17. [PMID: 21874528 DOI: 10.1007/s10142-011-0247-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 07/22/2011] [Accepted: 08/15/2011] [Indexed: 11/25/2022]
Abstract
Investigating the relationships between critical influenza viral mutations contributing to increased virulence and host expression factors will shed light on the process of severe pathogenesis from the systems biology perspective. We previously generated a mouse-adapted, highly virulent influenza (HVI) virus through serial lung-to-lung passaging of a human influenza H3N2 virus strain that causes low virulent influenza (LVI) in murine lungs. This HVI virus is characterized by enhanced replication kinetics, severe lung injury, and systemic spread to major organs. Our gene microarray investigations compared the host transcriptomic responses of murine lungs to LVI virus and its HVI descendant at 12, 48, and 96 h following infection. More intense expression of genes associated with cytokine activity, type 1 interferon response, and apoptosis was evident in HVI at all time-points. We highlighted dysregulation of the TREM1 signaling pathway (an amplifier of cytokine production) that is likely to be upregulated in infiltrating neutrophils in HVI-infected lungs. The cytokine gene expression changes were corroborated by elevated levels of multiple cytokine and chemokine proteins in the bronchoalveolar lavage fluid of infected mice, especially at 12 h post-infection. Concomitantly, the downregulation of genes that mediate proliferative, developmental, and metabolic processes likely contributed to the lethality of HVI as well as lack of lung repair. Overall, our comparative transcriptomic study provided insights into key host factors that influence the dynamics, pathogenesis, and outcome of severe influenza.
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Affiliation(s)
- Fransiskus X Ivan
- Computational and Systems Biology Program, Singapore-MIT Alliance, Singapore, Singapore
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16
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Narasaraju T, Ng HH, Phoon MC, Chow VTK. MCP-1 antibody treatment enhances damage and impedes repair of the alveolar epithelium in influenza pneumonitis. Am J Respir Cell Mol Biol 2009; 42:732-43. [PMID: 19617401 DOI: 10.1165/rcmb.2008-0423oc] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Recent studies have demonstrated an essential role of alveolar macrophages during influenza virus infection. Enhanced mortalities were observed in macrophage-depleted mice and pigs after influenza virus infection, but the basis for the enhanced pathogenesis is unclear. This study revealed that blocking macrophage recruitment into the lungs in a mouse model of influenza pneumonitis resulted in enhanced alveolar epithelial damage and apoptosis, as evaluated by histopathology, immunohistochemistry, Western blot, RT-PCR, and TUNEL assays. Abrogation of macrophage recruitment was achieved by treatment with monoclonal antibody against monocyte chemoattractant protein-1 (MCP-1) after sub-lethal challenge with mouse-adapted human influenza A/Aichi/2/68 virus. Interestingly, elevated levels of hepatocyte growth factor (HGF), a mitogen for alveolar epithelium, were detected in bronchoalveolar lavage samples and in lung homogenates of control untreated and nonimmune immunoglobulin (Ig)G-treated mice after infection compared with anti-MCP-1-treated infected mice. The lungs of control animals also displayed strongly positive HGF staining in alveolar macrophages as well as alveolar epithelial cell hyperplasia. Co-culture of influenza virus-infected alveolar epithelial cells with freshly isolated alveolar macrophages induced HGF production and phagocytic activity of macrophages. Recombinant HGF added to mouse lung explants after influenza virus infection resulted in enhanced BrdU labeling of alveolar type II epithelial cells, indicating their proliferation, in contrast with anti-HGF treatment showing significantly reduced epithelial regeneration. Our data indicate that inhibition of macrophage recruitment augmented alveolar epithelial damage and apoptosis during influenza pneumonitis, and that HGF produced by macrophages in response to influenza participates in the resolution of alveolar epithelium.
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Affiliation(s)
- T Narasaraju
- Infectious Diseases Program, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, 5 Science Drive 2, Kent Ridge 117597, Singapore.
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17
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Poh WP, Narasaraju T, Pereira NA, Zhong F, Phoon MC, Macary PA, Wong SH, Lu J, Koh DR, Chow VTK. Characterization of cytotoxic T-lymphocyte epitopes and immune responses to SARS coronavirus spike DNA vaccine expressing the RGD-integrin-binding motif. J Med Virol 2009; 81:1131-9. [PMID: 19475608 PMCID: PMC7166745 DOI: 10.1002/jmv.21571] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Integrins are critical for initiating T‐cell activation events. The integrin‐binding motif Arg‐Gly‐Asp (RGD) was incorporated into the pcDNA 3.1 mammalian expression vector expressing the codon‐optimized extracellular domain of SARS coronavirus (SARS‐CoV) spike protein, and tested by immunizing C57BL/6 mice. Significant cell‐mediated immune responses were characterized by cytotoxic T‐lymphocyte 51Cr release assay and interferon‐gamma secretion ELISPOT assay against RMA‐S target cells presenting predicted MHC class I H2‐Kb epitopes, including those spanning residues 884–891 and 1116–1123 within the S2 subunit of SARS‐CoV spike protein. DNA vaccines incorporating the Spike‐RGD/His motif or the Spike‐His construct generated robust cell‐mediated immune responses. Moreover, the Spike‐His DNA vaccine construct generated a significant antibody response. Immunization with these DNA vaccine constructs elicited significant cellular and humoral immune responses. Additional T‐cell epitopes within the SARS‐CoV spike protein that may contribute to cell‐mediated immunity in vivo were also identified. J. Med. Virol. 81:1131–1139, 2009. © 2009 Wiley‐Liss, Inc.
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Affiliation(s)
- W P Poh
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Singapore, Singapore
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